1. Field of the Invention
This invention relates to a vacuum cleaner and more particularly to a so-called upright vacuum cleaner having a mechanism to lift its rotating agitator brush off the floor when the cleaner is used in above-floor cleaning mode.
2. Related Background Art
Upright cleaners, particularly those equipped for above-floor cleaning tasks, feature a mechanical arrangement, whereby the rotating agitator brush is lifted clear of the floor on which the cleaner is standing when the body of the cleaner is in its upright position, thereby eliminating undesirable contact between the rotating agitator brush and the floor when the cleaner is used in above-floor cleaning mode.
Hitherto, this has been accomplished by mounting the axle of the front wheels of the cleaner on a pair of arms pivoted to the underside of the foot of the cleaner. A cam-follower then co-operates with a cam located on the lower surface of the pivotable body of the cleaner. Pivoting movement of the body relative to the foot causes the pair of arms to pivot about a horizontal axis, thereby raising or lowering the height of the wheels and thus raising or lowering the agitator brush.
One such arrangement is disclosed in GB1303352, which also discloses a manual suction nozzle-height setting arrangement so arranged that, following use of the cleaner for above-floor cleaning, the nozzle height returns to the height setting selected prior to the above-floor cleaning.
A commonly-used alternative to the above-mentioned arrangement is the manually-actuated sliding cam arrangement disclosed in EP0551069.
GB13108099 discloses an alternative arrangement, whereby a formation on the lower extremity of the pivotable body engages the upwardly-projecting end of a rod which runs forward beneath the motor and fan unit to actuate the front wheel axle height setting mechanism. The illustrated embodiment also incorporates a manual nozzle-height setting arrangement employing a Bowden cable actuated by a control knob located at the top of the upright body of the cleaner. The resulting mechanism involves a multi-part linkage which, so as to eliminate exposure to the surface being cleaned and thereby eliminate detrimental effects on the linkage and its pivots, is enclosed in a chamber in the base of the cleaner foot.
EP1985218 discloses a vacuum cleaner in which the upright cleaner body is connected to the foot by a tubular neck formed integrally with a transverse duct which is pivotally mounted to the foot. In such arrangements, the neck and the transverse duct serve to convey airflow between the foot of the cleaner and the upright body.
The arrangement of GB1303352 cannot be used in vacuum cleaners of the kind disclosed in EP1985218 where the motor and fan unit of the cleaner is located in the foot of the cleaner (as distinct from in the base of the upright body), due to the fact that the bulky motor and fan unit is located in the foot between the pivot point and the front wheels. Furthermore, the way in which the bodies of such vacuum cleaners pivot relative to the foot makes it impossible to operate a lifting linkage via a formation on the surface of the body.
Accordingly, an object of the present invention is to provide a vacuum cleaner of the kind having a motor and fan unit located in the foot with an arrangement suitable for lifting the agitator brush away from the floor.